Heat Loss:
Radiation-loss to ambient air
Convection-air currents
Conduction-direct contact with cooler object
Evaporation-sweating
Heat loss is reduced by phenothiazines, anticholinergics, B-Blockers, Ca-Blockers, Diuretics, Amphetamines, LSD, Cocaine, MAO Inhibitors
Heat Cramps
hyponatremia leading to muscle cramping, usually the calves, thighs, and shoulders.
Heat Tetany
hyperventilation leading to respiratory alkalosis
Heat Exhaustion
salt depletion from sweating, leads to hypovolemia and hypoperfusion. Patient will retain normal mental status and neurologic exam. Temperature may only be slightly elevated. The patient will look spent.
Heat Stroke
Need CNS dysfunction and Temp>40
Breakdown of central thermoregulatory control
Hyperpyrexia, altered mental status, neurologic findings, and possibly the absence of sweating
Can lead to NCPE, ARDS, LFT elevations, ATN, Hematuria, Rhabdomyolysis, DIC
Immediate, aggressive cooling down to <39° C using ice packs in groin and axilla, spray the patient continuously with water, place in front of fan.
Fluid loss is usually not large. Give 2 L of NS and then cut back to ~500 cc/hr.
ABG c Lactate, CBC, Lytes, LFTs, PT/PTT, UA and Myoglobin.
Shivering can be controlled with benzos or meperidine.
Antipyretics are not effective.
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